Buried heterostructure semiconductor laser device

A semiconductor laser device comprising a semiconductor substrate with a first conductivity type, an active layer above said substrate, and a cladding layer with a second conductivity type, in that order, resulting in a double-heterostructure, wherein two parallel grooves with a given distance therebetween are formed through portions of said cladding layer and said active layer toward said substrate, and a first burying layer with the first conductivity type, a second burying layer with the second conductivity type and a third burying layer with the first conductivity type are disposed, in that order, within and outside of said two grooves except for an entire area positioned between said two grooves, and moreover a semiconductor layer with a flat surface having the second conductivity type is disposed over said third burying layer and the entire area positioned between said two parallel grooves, and a laminated structure formed in each of the lateral outsides of said two grooves, said laminated structure comprising said semiconductor layer with the second conductivity type, said third burying layer with the first conductivity type, said second burying layer with the second conductivity type, said first burying layer with the first conductivity type, said cladding layer with the second conductivity type, and said substrate with the first conductivity type.